Influence of dysprosium substitution on the properties of cobalt‐zinc ferrite nanoparticles: Structural, magnetic, and dielectric perspectives

Abstract A hydrothermal synthesis approach was employed to fabricate Ni₀.₂₅Co₀.₅Zn₀.₂₅Dy ₓ Fe₂O₄ nanoparticles with Dy substitution levels of x = 0.000, 0.025, 0.050, 0.075, and 0.100. X‐ray diffraction analysis confirmed a single‐phase spinel structure, with average crystallite sizes decreasing from 32.98 nm in the undoped sample to 18.30 nm at the highest Dy content and a concomitant increase in interplanar spacing ( d (311) ) from 0.2526 to 0.2554 nm. Specific surface area values rose from 36.38 to 65.56 m 2 g −1 . Williamson–Hall analysis estimated a crystallite size of approximately 12.81 nm and a microstrain of −0.00303, indicating lattice distortion due to Dy incorporation. Fourier‐transform infrared spectroscopy revealed characteristic metal‐oxygen stretching bands at ~588 cm −1 (tetrahedral) and ~458 cm −1 (octahedral), with slight shifts upon Dy doping. Magnetic measurements demonstrated superparamagnetic behavior with saturation magnetization values ranging from 34.7 to 40.8 emu g −1 , while dielectric analysis showed frequency‐dependent permittivity, highlighting the potential of these materials for energy storage and magnetic applications.